binaryTreeRightView.cpp

#include <bits/stdc++.h>

using namespace std;
//  Definition for a binary tree node.
struct TreeNode
{
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode() : val(0), left(nullptr), right(nullptr) {}
    TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
    TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
};

class Solution
{
public:
    vector<int> rightSideView(TreeNode *root)
    {
        if (!root)
            return {};
        queue<TreeNode *> q;
        q.push(root);
        vector<int> rightView;
        while (!q.empty())
        {
            int n = q.size();
            for (int i = 0; i < n; i++)
            {
                TreeNode *curNode = q.front();
                q.pop();
                if (curNode->left)
                    q.push(curNode->left);
                if (curNode->right)
                    q.push(curNode->right);
                if (i == n - 1)
                    rightView.push_back(curNode->val);
            }
        }
        return rightView;
    }
};